The two pillars of design theory: Method of analysis and rhetoric

Since the 1960's, there have been many initiatives for promoting theoretical understanding on design. However, in spite of definite progress, there are several puzzles and anomalies in the current theoretical landscape of design. We present an interpretation of the evolution of design theorizing that throws new light on these puzzles and anomalies. We contend that in the modern time, there have been two hidden inspirational sources for design theorizing, namely the method of analysis and rhetoric. As they concern different situations, their prescriptions in many ways differ. However, without explicit recourse to the sources, these mutually incompatible prescriptions, along with associated concepts and terms, have been mixed up in a confusing way. It is proposed that these two influences to design theory and practice have to be disentangled, to be able to act like two pillars supporting the phenomenon of designing. We hypothesize that actual design assignments require the mobilization of ideas and support from both pillars.